APPARATUS FOR SEPARATING SOLIDS AND LIQUIDS

Abstract: Apparatus for separating liquid and solid material has an auger having an auger screw and a tubular housing extending around the auger screw, the tubular housing having an opening in the top thereof to allow the solid material to be deposited through the opening into the auger screw. A screen extends around the auger and is spaced radially outwardly from the tubular housing to allow a mixture of the solid material and the liquid to be introduced between the tubular housing and the screen, whereby the liquid can flow outwardly through the screen while at least a portion of the solid material is retained on the inner side of the screen. A motor is provided for rotating the screen about the auger to allow the thus-retained solid material to fall through the opening into the auger for removal by the auger, and a filter is provided for filtering the liquid which drains through the screen, the filter and the screen being co-axially rotatable.

Description: Description APPARATUS FOR SEPARATING SOLIDS AND LIQUIDS Technical Field The present invention relates to apparatus for separating solids and liquids and is useful, for example, but not exclusively, for the treatment of waste water, industrial effluents and mixtures of liquid and vegetable matter. Background Art It is known, in the treatment of sewage, to use a cylindrical screen or basket for separating liquids and solids. The cylindrical screen is formed by a plurality of co-axial circular bars or rings, which are spaced apart in the axial direction of the screen, and which extend around, and are spaced radially outwardly from an auger, which is co-axial with the screen. The auger is arranged with its axis upwardly inclined, and with the cylindrical screen at the lower end of the auger, so that a mixture of the solids and liquids can flow into a lower portion of the interior of the screen through a lowermost end of the screen. The liquid can then drain outwardly of the screen, between the bars, while the solid material is retained in the interior of the screen. This retained solid material is then deposited into the auger, through an opening in the top of the auger, by means of a rake rotating around the interior of the cylindrical screen. Instead of employing this arrangement, it has also been proposed to modify the shape of the screen so as to form, at the interior of the screen a plurality of radially inwardly directed recesses or pockets, and to rotate the screen about the axis of the auger, so as to cause the solid material to fall from these recesses into the auger. T Disclosure of Invention According to the present invention, there is provided apparatus for separating liquid and solid material, comprising an auger having an auger screw and a tubular structure extending around the auger screw, the tubular structure having an opening in the top thereof to allow the solid material to be deposited through the opening into the auger screw. A screen extends around the auger and is spaced radially outwardly from the tubular structure to allow a mixture of the solid material and the liquid to be introduced between the tubular structure and the screen structure, whereby the liquid can flow outwardly through the screen while at least a portion of the solid material is retained on the inner side of the screen structure. A motor is provided for rotating the screen about the auger to allow the thus-retained solid material to fall through the opening into the auger for removal by the auger, and a filter extends around the screen for filtering the liquid which drains through the screen structure. With the arrangement according to the present invention, the filter has a diameter substantially greater than that of the screen, thus providing a relatively large filter area in a relatively compact floor space. The radial dimension of the filter may be as large as required, while the screen remains relatively thin and can be readily backwashed to remove solids form the screen. Sprays may be provided, between the screen and the filter structure, and at the exterior of the filter structure, for cleaning the screen and the filter structure, which in the preferred embodiment of the invention are fixed relative to one another and rotatable about the axis of the auger. Brief Description of the Drawings The present invention will be more readily apparent to those skilled in the art from the following description of embodiments thereof, when taken in conjunction with the accompanying drawings, in which:- Figure 1 shows a diagrammatic view taken in longitudinal cross section, through parts of a waste water treatment apparatus; Figure 2 shows a broken-away plan view, taken in section along the line 2 - 2 of Figure 1, of part of a sedimentation tank in the apparatus of Figure 1; Figure 3 shows a view in vertical cross-section through a screen and a filter forming parts of the apparatus of Figure 1; Figure 4 shows a portion of the screen of Figure 3 on a enlarged scale; Figure 5 shows a view taken in vertical cross-section along the line 5 - 5 of Figure 3; Figure 6 shows a view taken in cross-section along the line 6 - 6 of Figure 3; Figure 7 shows a view in elevation of the screen, taken in the direction of the arrow A of Figure 3; Figure 8 shows a view in side elevation of a part of one the pockets of a screen forming part of the of Figure 3; Figure 9 shows a view in the axial direction of the screen, of the pocket part shown in Figure 8; Figure 10 shows a view in a radially inwardly direction of the pocket part of Figure 8; Figure 11 shows a view on an enlarged scale of part of Figure 9; Figure 12 shows a broken-away view taken in section along the line 12 - 12 of Figure 9; Figure 13 shows a diagrammatic view in axial cross-section through a modified rotor arrangement; Figure 14 shows a view in axial elevation of the rotor arrangement of Figure 13; Figure 15 shows an end view of a modified rotor, with an end plate of the rotor broken away to facilitate illustration; Figure 16 shows a view in section along the line 16-16 of Figure 15; Figure 17 shows a broken-away view in section through parts of the rotor of Figures 15 and 16; Figure 18 shows a broken-away view in elevation of parts of the rotor of Figures 15 and 16; Figure 19 shows a spacer plate; Figure 20 shows a view in section along the line 17-17 of Figure 18; and Figure 21 shows a tie bolt forming part of the rotor of Figures 15 and 16. Description of the Best Mode In Figure 1 of the accompanying drawings, reference numeral 10 indicates generally an apparatus for separating liquids and solids, which includes a settlement tank indicated generally by reference numeral 12. The settlement tank 12 is provided with vertical baffles 14, which extend transversely of the settlement tank 12 and which are staggered from one another in both the vertical and the horizontal directions so as to provide a vertically and horizontally serpentine path of flow through the settlement tank, as indicated by arrows in Figures 1 and 2. An inlet pipe 16 provided with a valve 18 supplies a mixture of liquids and solids into the interior of the settlement tank 12 at one end of the settlement tank 12, and this mixture then flows along the above-described serpentine path to the opposite end of the settlement tank 12. The baffles 14 are provided, along the bottom edges thereof, with pipes 18 having horizontally directed outlet openings for discharging air into the mixture for aerating and agitating the mixture. The pipes 18 are provided with a supply of compressed air by a compressor 20, which is driven by an electric motor 22 and provided with a compressed air tank 24, which is connected to the pipes 18 through pipes 25. The compressed air tank 24 may be replaced by a ventilator blower. The air flows into the compressor 20 through a first, lower air inlet duct 26, having a first air inlet end 28 in the settlement tank 12 above the level of the mixture of solids and liquids of the settlement tank 12, and through a second, upper air inlet end 30, which is open to the atmosphere. The apparatus 10 includes, at the right-hand end of the settlement tank, as viewed in Figure 1 , a rotatable screen and filter structure indicated generally by reference numeral 32, which has a horizontal axis of rotation extending in the longitudinal direction of the settlement tank 12 and comprises an inner rotor indicated generally by reference numeral 33, and an outer rotor indicated generally by reference numeral 34, which is co-axial with the inner rotor 33. The inner rotor 33 extends around and is coaxial with an auger screw 38, which has a shaft 40 and a tube 42 extending around the auger screw 38 and forming a tubular housing for the auger screw 38. The inner rotor 33 is supported on the auger tube 42 by means of bearings 44 (Figure 3), which allow the inner rotor 33 to rotate about the auger tube 42. An internally- toothed ring gear 46 secured to one side of the inner rotor 33 meshes with a pinion 48 on the output shaft of a reduction gearing 49 driven by an electric motor 50, so that upon energization of the motor 50 the ring gear 46 is driven by the pinion 48 to cause the rotation of the inner rotor 33 about the auger tube 42. The outer rotor 34 is supported at its right-hand side, as viewed in Figure 1, by means of a bearing 52 on the auger tube 42 and, at its opposite side, on a pair of support rollers 54 (Figure 5) in rolling engagement with the inner periphery of an annular end wall 56. The support rollers 54 are rotatably mounted on a triangular support 55, which is mounted on a pedestal block 56 at one end of the auger tube 42. The pedestal block 56 is in turn supported in a horizontal I-beam 58 (Figure 1) extending across the width of the settlement tank 12. An electric motor 60 (Figure 3), through a reduction gearing 62, drives a pinion 64 meshing with a ring gear 66. The ring gear 66 is mounted on a circular side wall 68 at the right-hand side of the outer rotor 34, the bearing 52 being attached to the side wall 68. By energization of the electric motor 60, the outer rotor 34 is rotated about the auger tube 42. As shown in Figure 6, the inner rotor 32 comprises a screen 70, which in the present embodiment of the invention is made of metal mesh but which may alternatively be made of cotton, polyvinylchloride or another material. The screen 70 is shaped to form radially outwardly extending, radially inwardly open filter chambers or "pockets" 72, which are equiangularly spaced around the auger tube 42 and which are spaced from one another by radially outwardly open spaces 74. In the present embodiment, eight of the pockets 72 are provided, but it is alternatively possible to employ a greater number of pockets. The screen 70 is supported on rods 76, opposite ends of which are secured to a first circular side wall 78 carrying the ring gear 46 at one side of the inner rotor 32, and to a second circular side wall 80 at the opposite side of the inner rotor 32. The side wall 78 closes off the spaces 74 between the pockets 72 from the tank 12 and is formed with eight openings 79 (Figure 5) through which the liquid and solids in the tank 12 can flow into the screen pockets 72 of the inner rotor 33, as described in greater detail below. Figure 6 also shows four spray pipes 84 located between the inner and outer rotors 32 and 33 and provided with spray nozzles 86, which are directed so as to spray radially inwardly onto the mesh 70 and into the radially outwardly open spaces 74. Between t e spray pipes 84 and the outer auger 33 there is provided a cylindrically arch-shaped baffle or cover 83 which extends over the top of the inner rotor 32 and which is provided, at opposite sides of the cover 82, with inclined gutters 85. A weir structure 86 (Figure 3) in the settlement tank 12 has, at a semi-circularly curved upper edge 85 of the weir structure 86, a semi-circular seal 87, which is in sliding, sealing contact with a side face of the ring gear 46 around the lowermost half of the ring gear 46. The weir 86 and the seal 87 ensure that the mixture of solids and liquids flowing through the settlement tank 12, in the direction of the arrows of Figure 1, flows firstly through the openings 79 in the side wall 78 and into the pockets 72 of the inner rotor 32 and then passes through the screen 70 before passing radially outwardly through the outer rotor, as described below. Solid material which is retained within the pockets 72 of the inner rotor 32 at the lower half of the inner rotor 32 is carried upwardly on the screen 70, as the inner rotor is rotated bj the electric motor 50, until it is dislodged by water directed radially inwardly from the spray nozzles 86. The rotation of the upper rotor 33 and the spraying from the spray nozzles 86 are effected intermittently, at time intervals which are selected in accordance with the rate of deposition of the solid material on the screen mesh 70 in the pockets 72. Within the filter 32, the auger tube 42 has an upwardly directed opening 44, through which the solid material which is dislodged by the sprays from the spray nozzles 86 and by gravity from the pockets 72 is deposited into the auger 38. The shaft 40 of the auger 38 is rotated by an electric motor 90 through a reduction gearing 92. The rotation of the auger screw shaft 40 causes the solid material deposited into the auger 38 to be fed along the auger tube 42 for discharge through an outlet pipe 94 into a container (not shown) or the like. The construction of the pockets 72 of the inner rotor 32 is illustrated in greater detail in Figs. 8 through 12. Each of the pockets is formed by a pair of generally L-shaped mesh structures, one of which is indicated generally by reference numeral 120, and is formed of metal mesh material 122, the edges of which are held in a frame 124. The mesh material 122 is supported, between opposite sides of the frame 124, by support wires 126, the ends of which are secured in the frame 124. At each of the pockets 72, the outer edges of the mesh structures 120 are connected together by connectors 128, and opposite sides of the frames 124 are slid into engagement with slots in connector strips 130. The inner ends of the frames are slid into contact with channel-shaped spacers 132, which are mounted on rods 134 extending between the opposite wall 78 and 80 of the inner rotor 33. The outer rotor 34 forms a filter structure and has three annular walls 140 extending transversely of the axis of rotation of the outer rotor 34. The wall 140 are secured to one another and to the opposite side walls 56 and 68 of the outer rotor 34 by means of rods 141 (Figure 5). The outer rotor is packed with sand 146, which serves as a filter medium. Other filter media, e.g. ceramic filter material or activated charcoal or a combination of different filter media, may be substituted for the sand 146. Inner and outer heavy wire meshes 142a, sandwiched with fine sand retention meshes 142b and inner micromeshes 142c, serve to retain the sand radially. To prevent the sand from being displaced around the outer rotor 34 as the latter rotates, radially extending bulkheads 145 (Figure 6) are equiangularly spaced around the outer rotor 34. The liquid which passes radially outwardly through the screen 70 of the inner rotor 33 then passes through the sand 146 of the outer rotor 34 and is retained in an end portion 148 of the tank 12, which is provided with an overflow pipe 150, through which the filtered liquid can flow from the tank end portion 148. The weir structure 86 is provided with a semi-circular seal 152, in sliding, sealing contact with the side wall 56 of the outer rotor 34. The seal 152 ensures that the liquid which has passed through the screen 70 of the inner rotor is retained in the outer rotor 34 until it flows through the sand 146. A water pipe 153 with spray nozzles 155 is provided above the outer rotor 34 for back- washing the sand 146. The compressor 20, the motor 22 and the tank 24, the inner and outer rotors 33 and 34, the auger 38, and the end portion 148 of the tank 12 are all accommodated within an air-tight enclosure, indicated generally by reference numeral 160, which includes an end wall 162 and a roof 164. The settlement tank 12 is provided with a flexible cover 166, which can close off the top of the settlement tank 10 from the atmosphere. Consequently, noxious fumes from the liquid and solids being processed can be retained within the interior of the settlement tank 10 and the enclosure 111, so as to avoid pollution of the surrounding atmosphere. Figure 13 shows a modification in which the inner rotor 33 of Figure 3 is replaced by a rotor 33a which is spaced axially from a rotor 34a, which replaces the rotor 34 of Figure 3. The construction of the rotor 33a is similar to that of the rotor 33, but the rotor 34a is a modification of the rotor 34, as can be seen from Figure 14. More particularly, the filter material, which is indicated by reference numeral 200 and which comprises charcoal, activated carbon or lightweight ceramic filter medium, is contained between a cylindrical outer mesh material 202 and an inner mesh material indicated generally by reference numeral 204. The inner mesh material 204 comprises radially extending portions 206 which are connected by inner cylindrically curved portions 208 and outer radially curved portions 210 so as to form radially inwardly open recesses or pockets 212. The filter material 200 thus forms radially inwardly projecting walls 214. In this way, the effective filter area of the rotor 34a is substantially increased relative to that of the filter 34 of Figure 3. The path of the liquid through the rotors 33a and 34a is indicated by the arrow line A- A of Figure 13, from which it can be seen that the liquid firstly passes radially outwardly through the rotor 33a, and then enters the interior of the rotor 34a through the pockets 212 and flows radially outwardly through the filter material 200. Water sprays 220 and 222 are provided for back-flushing the rotors 33a and 34a, respectively, for periodically clearing them. The rotor 34a includes a cylindrical baffle or cover 224 formed with gutters 226 at opposite sides and spaced inwardly from the inner cylindrically curved portions 208 for catching the liquid used for back-flushing the rotor 34a and discharging it axially from the rotor 34a. The space between die inner and outer mesh materials 202 and 204 is closed at the left- hand side of the rotor 34a, as viewed in Figure 13, by a correspondingly-shaped plate 227, which leaves the left-hand side of the pockets 112 open. The plate 227 has bee omitted form Figure 14 to facilitate the illustration of the rotor 34a. The opposite side of the rotor 34a is closed by a circular plate 228, and the filter material 200 is also retained by radial partition walls 230. Weirs 232 and 234, provided with semi-circular seals 236 and 238 in sealing contact with the rotors 33a and 34a, prevent the flow of the liquid from by-passing its above- described course through the rotors 33a and 34a. Figures 15 to 21 illustrate a modified form of construction which may be employed for hte rotors 33 and 33a. As shown m Figures 15 to 21, the rotor is in the form of a screen which has end plates 330 and 332 with a plurality of bars indicated generally by reference numeral 334 spaced apart from one another along the length of the screen 302. Each of the bars 334 is formed of a curved outer metal strip 336 connected to a pair of straight inner metal strips 338. The bars 334 are provided in groups of three different sizes, so as to present, along the length of the inner periphery of the screen 302, a series of steps, as shown in Figure 16, forming a plurality of axially spaced annular recesses 340. The bars 334 also form recesses or pockets 342 which extend radially outwardly. The bars 334 are secured together by rods 346, which are secured at opposite ends to the end plates 330 and 332 and which connect the largest bars 334, and also by sub- assembly tie bolts, as indicated generally by reference numeral 348, which connect together the groups of bars 334, together with spacer plates 350 provided between the bars 334. As shown in Figure 17, metal strips 352, which have a width in the radial direction of the screen which is greater than that of the remainder of the bars 334, serve to interconnect the groups of bars 334. As will be apparent to those skilled in the art, various modifications may be made to the above -described apparatus within the scope of the invention as defined by the appended claims.

Claims: Clai s 1. Apparatus for separating liquid and solid material, comprising: an auger; said auger comprising an auger screw and a tubular housing extending around said auger screw; said tubular housing having an opening in the top thereof to allow the solid material to be deposited through the opening into said auger screw; a screen extending around said auger and spaced radially outwardly from said tubular housing to allow a mixture of the solid material and the liquid to be introduced between said tubular housing and said screen, whereby the liquid can flow outwardly through said screen while at least a portion of said solid material is retained on the inner side of said screen; means supporting said screen for rotation about said auger; means for rotating said screen about said auger to allow the thus-retained solid material to be deposited through said opening into said auger for removal by said auger screw; a filter for filtering the liquid which drains through said screen; means supporting said filter for rotation; and means for rotating said filter. 2. Apparatus as claimed in claim 1, where in said filter and said screen are co- axial, and further comprising spray nozzles between said screen and said filter and directed towards the outer surface of said screen, around an upper portion of said screen, for cleaning said screen. 3. Apparatus as claimed in claim 1, further comprising spray nozzles directed towards the outer surface of said filter, around an upper portion of said filter, for cleaning said filter. 4. Apparatus as claimed in claim 3, further comprising a cylindrically curved baffle between said screen and an upper portion of said filter for deflecting away from said screen liquid from said screen liquid from said spray nozzles which seeps radially inwardly through said filter. 5. Apparatus as claimed in claim 1, wherein said screen comprises a screen shaped to form a plurality of radially outwardly extending screen recesses which are spaced around said auger, said screen recesses being open radially inwardly towards said auger, said recesses also being open at one side of said screen for receiving an inflow of liquid and solids into said recesses. 6. Apparatus as claimed in claim 1, further comprising a tank for receiving a mixture of solids and liquid, said tank having an arrangement of vertical baffles for deflecting the flow of said mixture along said tank and air outlets for aerating the mixture in said tank, and an outlet for the flow of the mixture into said screen. 7. Apparatus as claimed in claim 6, wherein said outlet is formed by a vertically circularly curved weir extending across said tank and a seal between said weir and one side of said screen. 8. Apparatus as claimed in claim 1, wherein said filter comprises an annular filter formed of paniculate material for filtering the liquid from said screen and inner and outer mesh structures for retaining said particulate material.

Inventors: ABEL GUNTHER, ABEL, GUNTHER
Applicants: ABEL GUENTHER, ABEL, GUNTHER
Application year: 1994
Main classification: B01D33
IPC codes: B01D21, B01D24, B01D33